System of current rectification.



C. LE 6. FORTESCUE. SYSTEM OF CURRENT RECTIFICATION. APPLICATION FILED JUNE 21. 1912.

1,158,474. Patented Nov. 2, 1915.

3SHEET$SHEET I. 59/. 2 I

ATTORNEY C. U: G. FORTESCUE. SYSTEM OF CURRENT RECTIFICATION.

APPLICATION FILED JUNE 21. 1912.

1,158,474. Patented Nov. 2, 1915.

3 SHEETSSHEET 2.

TNESSES: INVENTOR lggj 4 400. 5 9m ATTORNEY UNITED STATES PATENT onnrcn.

CHARLES LE G. FORTESCUE, OF PITTSBURGH, PENNSYLVANIA, ASSIGNOR TO WEST- INGHOUSE ELECTRIC AND MANUFACTURING COMPANY, A CORPORATION OF PENN- SYLVANIA.

SYSTEM OF CURRENT RECTIFICATION.

Application filed June 21, 1912. Serial No. 705,017.

T 0 all whom it may concern:

Be it known that 1, CHARLES Ln G. FOR TESGUE, a citizen of the United States, and a resident of Pittsburgh, in the county of Allegheny and State of Pennsylvania, have invented a new and useful Improvement in Systems of Current Rectification, of which the following is a specification.

My invention relates to systems of electrical distribution, and particularly to systems in which vapor and similar currentrectifying devices are employed for transforming alternating into direct currents.

The object of my invention is to provide a polyphase system of distribution in which all of the phases of the current are rectified to produce a substantially non-fluctuating direct current, and in which there is no possibility of the occurrence or existence of local or circulating currents.

My invention is illustrated in theaccompanying drawing, Figure 1 of which diagrammatically illustrates a system of dis tribution embodying the same. Figs. 2, 3, 4 and 5 are similar views of modifications of the system of Fig. 1, and Fig. 6 is a simplified diagram of a part of the system of Fig. 5.

The systems of Figs. 1 and 2 comprise a polyphase supply circuit 123 that supplies current to a plurality of transformer 7 this will generally be found to be the preferable'arrangement, though, if desired, they may be connected in star relation, as shown in Fig. 2, or they may be otherwise suitably arranged without de arting from the spirit of the invention. Eorresponding to the several primary windings are secondary windings 7, 8 and 9, respectively, and corresponding to the secondary windings are mercury-vapor or other suitable currentrectifying devices" 10, 11 and 12, the anodes of which are respectively connected to terminals at or adjacent to the ends of the secondary windings. The cathode of the rectifier 10 is connected to one of the conductors 13 of a direct-current distributing circuit,

Specification of Letters Patent.

Patented Nov. 2,1915.

way system, etc. The neutral or another suitable intermediate point 14 of the' secondary winding 7 is connected to the cathode of the rectifier, 11, and the corresponding ntermediate point of the secondary windmg 8 is connected to the cathode of the rectifier 12, while the corresponding intermediate point of the secondary winding 9 is connected'to the other conductor 15 of the direct-current distributing circuit. It will be observed that the transformer secondary windings. are separate from each other to such degree that it is impossible for locally circulating currents to traverse them, which is the case in some systems heretofore provided by reason of the fact that two of the polyphase electromotive forces simultaneously have appreciable values of the same polarity. In the present system, the rectifiers are, in effect, connected in series relation, and the voltage of the direct-current circuit is, therefore, the sum of the unidirectional electromotive forces produced at the same time by the three rectifiers, which voltage will have a substantially uniform value, as distinguished from one which pulsates. reason of the series connection of the rectifiers, each rectifier is independent of the others to such an extent that the drops of potential in them may vary freely With-' out detrimentally affecting the operation of the system or causing the flow of local currents. As a consequence, the power factor and efficiency of operation of the system are both high.

, The invention is not limited in its application to a 3-phase supply system but may also be em loyed in connection with a 2- phase supp y circuit 17, as shown-in Fig. 3, in which two transformers are employed having their primary windings 18 and 19, respectively connected to the differently phased pairs of conductors of the said circu1t, he 1 connections of the secondary wind gs ,of,the'--sa1d transformers are substantially" the same as shown in Figs. 1 and 2, except that only two rectifiers are employed. The operation of the system of Fig. 3 is also substantially the same as those of Figs. 1 and 2, though the rectified current will fluctuate somewhat in value, and, for this reason, an impedance coil 20 is preferably employed in the direct-current distributing circuit.

It may often be desirable to obtain a substantially non-fluctuating rectified current from a 2-phase distributing circuit, and, to this end, suitable transforming means may be employed for changing 2-phase current into 3-phase current for application to three rectifiers, the said transformers being so arranged as to provide neutral or intermediate points which may be connected to the directcurrent distributing circuit or to the cathodes of certain of the rectifiers. -One such system is shown in Fig. 4 in which the primary windings 21 and 22 of two transformers are respectively connected to the differently phased pairs of conductors of a two-phase supply circuit 23. Each of the transformers is provided with a plurality of secondary windings, the windings 26 and 27 corresponding, respectively, to the primary winding 21 and the secondary windings 28, 29 and 30 corresponding, respectively, to the primary winding 22. The convolutions of the secondary windings 26 and 27 are 86.6% of the convolutions in the secondary winding 7 28, and theconvolutions in the secondary formers 31 and 32.

windings 29 and 30 are 50% of the convolutions in the winding 28. Terminals of the secondary windings 26 and 29 are directly connected together and the remaining terminals are connected by means of an auto transformer 31. Similarly, terminals of the secondary windings 27 and 30 are directly connected together, and an auto transformer 32 is connected between the remaining terminals thereof. The anodes of a rectifier 34 are respectively connected to the terminals of a secondary winding '28, and the anodes of rectifiers 35 and 36 are respectively connected to the terminals ofthe auto transrectifier 35 is connected to one conductor 37 'of""al'direct-current distributing circuit, and

the cathodes'of the rectifiers 34 and 36 are respectively connected to intermediate points of the transformer windings 31 and 28, while an intermediate point of the transformer winding 32 is connected to-the remaining conductor 38 of the direct-current distributing circuit.

It will be understood, from the arrangements of the connections shown, that 2- phase current received from the supply circuit 23 is changed to 3-phase current for application to the rectifiers, and that, according to the principles set forth in connection with Fig. 1, the three-phase currents are changed by the rectifiers to a substantially non-fluctuating or uniform direct current.

Another systemin which 2-phase current is transformed to 3-phase current and supplied to three rectifiers is shown in Fig. 5, in which two transformers 40 and 41 are I employed, the primary windings of which The cathode of the secondary windings 45, 46, 47 and 48, the

convolutions of each of which are approximately 43% of the convolutions of the winding 42.

p The terminals of the secondary winding 42 are respectively connected to the anodes of a rectifier 49, and an intermediatepoint of the said winding is connected to the cathode of another rectifier 50. The anodes of the rectifier 50 are respectively connected to terminals of the secondary windings 45 and 46 that are connected in series relation with each other and with the secondary winding 44, which is interposed between them. An intermediate point of the secondary winding 44 is connected to the cathode of a third rectifier 51, the anodes of which are respectively connected to terminals of the secondary windings 47 and 48 that are connected in series relation with each other and with the secondary winding 43, which is interposed between them. The winding 43 is connected in series with the windings 47 and 48 in inverse relation to the manner in which the winding 44 is connected in series with the windings 45 and 46. An intermediate point of the-winding 43 is connected to one conductor 52 of a suitable direct-current distributing circuit and the other conductor of the said circuit is connected to the cathode of the rectifier 49.

A diagram showing only the connections of the secondary wind gs of the transformers to the rectifiers is shown in Fig. 6, the secondary windings being arranged to illustrate more clearly the relations of the elec tromotive forces which are applied to the rectifiers. It will be readily seen, particularly from the diagram of F ig. 6, that the electromotive forces applied to the rectifiers are disposed 120 apart, or bear the relations to each other of electromotive forces of a three-phase circuit. Consequently, the rectifier current will have a substantially uniform or non-fluctuating value, as in the systems of Figs. 1 and 2.

I claim as my invention:

1. A system of distribution comprising a polyphase supply circuit, transformers ha"- ing primary windings associated, respectively, with conductors of different phases of said circuit, each of said transformers having a plurality of secondary windings, current rectifiers one of which has its anodes connected to the respective terminals of one of the said secondary windings and each of the others of which has its anodes respectively connected to the terminals of different of the remaining secondary windings which are connected together in groups, a distributing circuit the conductors of which are respectively connected to the cathode of one rectifier and an intermediate point of a secondary Winding that is not connected to the latter rectifier, and connections between the cathodes of the remaining rectifiers and intermediate points of the remaining secondary windings.

2. A system of distribution comprising a two-phase supply circuit, transformers having primary windings associated, respectively, with conductors of different phases of said circuit, one of said transformers having three secondary windings two of which have approximately one-half the con- .Volutions of the other winding, and the other transformer having four secondary wind ingseach having approximately 43% of the convolutions of the larger winding of the aforesaid transformer, the latter secondary anodes respectively connected to the terminals of the long transformer secondary winding and the others of which have their anodes respectively connected to the terminals of the two series sets of secondary windings, means connecting the reetifiers in series relation, and a distributing circuit supplied from the rectifiers.

In testimony whereof, I have hereunto subscribed my name this 18th day of June, 1912.

CHARLES LE e. FORTESCUE.

Witnesses:

O'r'ro S. SOHAIRER, B. B. HINES. 

